The present invention relates to a cover element having through-holes and blind holes as well as a hole-free rim, wherein the cover element is produced from a plastics material by injection molding.
Cover elements or grille elements of this type are known in the automotive industry and, for example, can cover recesses or openings in vehicle doors, in the dashboard, or in other motor vehicle elements. For example, air ventilation outlets or loudspeakers can be covered. When creating grille structures having geometrical hole patterns, if the cover edges are trimmed or shaped in a manner deviating from the geometrical arrangement, there occur regions of different sizes in which truncated holes would be created having a size that is below what can be obtained by the production process. Consequently, the truncated holes are dropped from the pattern and an imperfect edge pattern is thus formed.
In the case of covering loudspeakers, the grille element is subject to specific requirements in terms of the acoustics of the loudspeaker. In this case, the grille elements are referred to as loudspeaker grilles. The desired acoustic performance dictates a total area and layout of open holes through which sound and air can pass. When producing loudspeaker grilles as an integrated component, the grille hole pattern may continue into a rim or edge region of the cover element using blind holes which do not penetrate through the grille element. A more pleasing appearance is provided by the continuation of a uniform hole pattern across a greater portion of the grille. At the edge of the pattern, however, the holes are subject to limits imposed by the production process. It is typically not possible to produce a truncated hole with a hole size less than half the diameter of a hole. A frayed, imperfect, undesired appearance is produced by the omission of this grille pattern in this edge region.
In order to overcome this visual problem, the hole pattern could be changed toward the edge region so that holes that are as complete as possible (i.e., holes that are unchanged in terms of their geometry) are produced. This is generally achieved by changing the distance between the holes or by scaling the hole size. Interrupted patterns, which at best are considered to be less objectionable than imperfect outer contours, are produced by this interference with the uniformity of the grille arrangement. The creation of such geometries involves great effort and may take up to four days or more for a designer to develop, depending on the design and grille size, if each hole has to be created individually. In addition, it is necessary to repeat this effort for each new grille element being developed for different products (e.g., models of vehicles).
For a speaker grille, all of these additional efforts to develop modified hole patterns may have an undesirable affect on the acoustic properties. The ideal acoustic property of a loudspeaker grille would allow an air flow of 50%. Depending on the component, different materials are used in production by injection molding. The specific material properties influence the necessary dimensions of the webs as a result of their specific fluidities. The size of the hole diameters thus depends on the acoustic parameters and may be minimized by the necessary web width. The greatest air flow is achieved with offset holes. One ideal shape is hexagonal holes similar to a honeycomb. This geometry does not allow any change or adjustment of the holes by different sizes and distances.
Based on the foregoing, an object of the present invention is to provide a grille element which can be designed and produced quickly and as easily and advantageously as possible by simple means, it being possible at the same time to achieve an uninterrupted hole pattern.